Helen and David talk to historian Adam Tooze about his epic new book Crashed: How A Decade of Financial Crises Changed the World. Why did the crash of 2008 take so many people by surprise? How did it spread from the US around the world? Why was Europe so vulnerable? And how do the answers to these questions help explain Brexit, Trump and what's now going on in places from Hungary to China? Plus, as we approach the 10-year anniversary of the event the triggered the crisis, we explore what might have happened if Lehman Brothers had been saved.